This invention generally relates to intravascular catheters suitable for maintaining the patency of a body lumen during delivery of a radiation source to the body lumen. In typical percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and is advanced therein until the distal tip thereof is in the ostium of the desired coronary artery. A guide wire and a dilatation catheter having an inflatable balloon on the distal end thereof are introduced through the guiding catheter with the guide wire slidably disposed within an inner lumen of the dilatation catheter. The guide wire is first advanced out of the distal end of the guiding catheter and is then maneuvered into the patient's coronary vasculature containing the lesion to be dilated, and is then advanced beyond the lesion. Thereafter, the dilatation catheter is advanced over the guide wire until the dilatation balloon is located across the lesion. Once in position across the lesion, the balloon of the dilatation catheter is filled with radiopaque liquid at relatively high pressures (e.g., greater than about four atmospheres) and is inflated to a predetermined size (preferably the same as the inner diameter of the artery at that location) to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the artery. The balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the dilated artery.
After an angioplasty procedure, restenosis at or near the site of the original stenosis in the artery occasionally occurs. The smooth muscle cells of the artery may proliferate at the site of angioplasty treatment. Restenosis may result in a reformation of the lesion and a narrowing of the artery at the site.
Various devices and methods for the prevention of restenosis have been developed, including the use of an expandable stent on the distal end of the catheter designed for long-term implantation in the body lumen. Other devices and methods for the prevention of restenosis after angioplasty or another arterial intervention procedure employ a radiation source delivered through a balloon. The radiation operates to destroy the proliferating cells thereby preventing development of restenosis.
There is a need in the art for a catheter with a minimal profile having an expandable region which can maintain the patency of an artery and allow delivery of a radiation source to the treatment area for a period of time sufficient to prevent development of restenosis. Such an intravascular catheter should be easy and inexpensive to manufacture, have an expandable region that is strong and reliable under pressure, and be capable of forming a variety of shapes to allow flexibility in the amount and pattern of expansion and deformation of the expandable region. Further, the associated radiation source should be protected from any contact with the body fluids of the patient in order to allow the radiation source to be reused. The present invention fulfills these needs.